Label magazines are commonly used to provide a supply of labels for an apparatus which applies labels individually to articles such as, labellers used to apply labels to containers in the packaging industry. An example of such a label magazine is disclosed in U.S. Pat. No. 3,450,586. A stack of labels is placed in the label magazine where a device is provided for advancing the stack of labels towards the label picker for removing the labels individually from the magazine. The labels are advanced by the use of a coiled spring which biases a plate against the stack of labels which in turn continually pushes the stack of labels against the label picker. Such system has proven satisfactory, however, in some situations depending upon the type of label to be dispensed, the working environment, the diecutting of the stack of labels, and surface coatings on the labels can all cause the labels to stick to one another which results in a problem in removing labels individually from the magazine. The above problem is aggravated by the use of the system of the above U.S. patent which continuously applies a relatively constant pressure on the stack of labels for pushing them against the label picker.
Considering the aspects which cause the labels of a stack to stick to each other, in the diecutting of the labels in a one stroke press, if the cutting dyes become blunt this can cause labels of the stack to become physically attached to another. In the printing of labels, the speeds of production demand that sheets of labels be stacked together possibly before the printing inks are totally dry. Embossed designs tend to mechanically lock individual labels together. Gold effect finishings on labels can result in a sticky surface which can cause adherance of labels in the stack. Surface coatings on the labels which seal the printed face can also cause an imbalance in the paper stock so that humidity variations can cause bending or curving of the labels. It has been found that the continual pressure on a stack of labels having one or more of the above drawbacks, in a dispensing magazine significantly increases the problem of separating individual labels from the face of the label stack.
Other systems used for advancing labels in a label magazine involve vibrating devices. It has been found however that with the use of vibrating systems the continual high frequency vibration for advancing the labels toward the picking device causes substantial compaction in the stack of labels and thus results in the same problem of interfering with the ease in separating individual labels from the face of the label stack. In addition, the vibrating mechanism tends to shock the magazine and cause a mechanical loosening or freting of the magazine components and wearing of contacting faces of the components. Examples of such vibrating mechanisms as used in advancing sheets in a stack of sheets are disclosed in U.S. Pat. Nos. 3,334,890 and 3,545,741.
This invention provides a system for advancing the labels in a manner which provides for an intermittent force on the label stack to advance same without aggravating the problem of removal of individual labels from the stack, and thereby provide a more reliable label dispensing.